I had this same problem so I called Rockstar. The lady on the phone told me to erase the game data (the original install and the game saves) and then start over. I did what she told me to do and the freezing problem went away.
And can the person who made this thread please include this information in the original post?
Edit: I have a 60GB NTSC launch unit.
We have no idea if this is correct, but, you know. Keeping you informed, and all. Let's hope it doesn't start locking up after you've got the first ten hours under your belt, eh?